It is conventional to incorporate finely powdered grains or matting agents into the protective layer of a photographic element to increase the surface roughness to achieve the following: (1) reduce self-adhering of the material, (2) reduce sticking of the material to manufacturing and processing devices, (3) improve the antistatic properties of the material, and (4) improve the vacuum adhesiveness of the material in contact exposure to prevent Newton's rings. The matting agents are commonly very small particles of organic or inorganic materials, such as silicone dioxide, magnesium oxide, titanium dioxide, calcium carbonate, poly(methyl methacrylate), poly(vinyltoluene), poly(methyl methacrylate-co-methacrylic acid), and so on.
Matting of the protective layer suffers, however, from various disadvantages. For example, it reduces the transparency of the photographic elements after processing and increases the graininess of the picture. It has been heretofore known to include processing removable polymer particles, sometimes referred to as soluble matte, in protective layers. High concentrations of processing removable matte are needed especially when the unprocessed photographic elements are used or stored at high relative humidities and at elevated temperatures of from 30 to 40.degree. C. High concentrations are also needed to prevent contact specks which cause adverse sensitometric defects when the unprocessed materials are rolled up.
The use of a high level of processing removable matte provides a satisfactory solution to conventional films for amateur use, for which the processed, or developed, film strips are returned to the consumer in synthetic resin pouches, or sleeves, where the frontside and backside of the film do not come in contact with each other.
Recent patents have disclosed photographic systems where the processed element may be re-introduced into a cassette. This system allows for compact and clean storage of the processed element until such time when it may be removed for additional prints or to interface with display equipment. Storage in the cassette is preferred to facilitate location of the desired exposed frame and to minimize contact with the negative during subsequent usage. U.S. Pat. No. 5,173,739 discloses a cassette designed to thrust the photographic element from the cassette, eliminating the need to contact the film with mechanical or manual means. Published European Patent Application 0 476 535 A1 describes how the developed film may be stored in such a cassette. The dimensions of such a so-called thrust cassette requires that the processed photographic element is wound tightly and under pressure, causing direct close contact between the front and back sides which results in ferrotyping, especially at high temperature and high relative humidity. Processing removable matte does not prevent this problem.
In recent years, rapid processing and high temperature drying after processing have become common practice for photographic materials. The high temperature dried films, for example 60.degree. C. (harsh drying), tend to aggravate ferrotyping which results from close contact, especially under elevated humidity and temperature. When ferrotyping is sufficiently severe, the resulting prints are unacceptable. Films dried at lower temperatures, for example 40.degree. C. (mild drying), tend to show much less ferrotyping. The reason for this difference is not understood.